Most open cut grain harvesters have knife guard fingers fitted to the cutting platform as original equipment, and this invention is limited to use with such platforms. Knife guard fingers are usually arranged in spaced array across a platform in a horizontal plane, and the platform vertically adjusted to travel at a selected height through a crop. The elongate fingers have knife receiving slots which guide knife cutting blades. These blades reciprocate in a transverse direction in relation to the longitudinal axis of the elongate fingers. The stalks of the crop are guided to the cutting blades by the knife guard fingers and subsequently cut, the stalks bearing against the knife guard fingers.
The most common arrangement is to have the knife guard fingers fixed to the cutting platform at intervals such that the pitch, or centre-to-centre spacing is 76 mm. The knife guard fingers are normally arranged in pairs, each finger being attached to a transverse mounting bar on the platform.
Each pair is fastened to the cutting platform by a pair of nuts and bolts which pass through holes in lugs which are also spaced at intervals of 76 mm along the cutting platform and which correspond to mounting holes in the mounting bar of the platform. Each finger projects forwardly of a respective lug.
The applicant is aware of a need whereby the knife guard fingers are at reduced intervals, and in particular half of the interval distance currently used; in other words 38 mm. This need has arisen as a result of the advent of double-cut knife sections, which are more advantageous when used in shatter-prone crops or when harvesting at higher than normal speeds. By increasing the number of fingers, and reducing the pitch, the crop is subject to less shaking by the knives as they cut, and there is much less loss due to "shatter". Incidence of knife section breakage is also reduced.
However, the need also still exists for the use of the original 76 mm spacing, especially when dealing with heavy weed situations or for the harvesting of thickly stemmed crops, or down entangled crops (lodged crops).
Presently, the only alternatives available to convert to a new spacing are to either modify the existing knife guard fingers by cutting and welding, or to purchase a new set of knife guard fingers with the required spacing. Whilst these are technically satisfactory, they do have their disadvantages. Consideration of such alternatives show that both of the methods involve additional costs and prove most time consuming having regard to fabrication requirements and the change-over time required to change from one set to the other.
It is the main object of the present invention to provide means whereby the pitch, or centre spacing, of original equipment knife guard fingers (for example, made in pairs) can be quickly and easily altered.
It is a further object of this invention to provide a new and improved knife guard finger attachment that can be used in association with original equipment guard fingers on commonly used harvesting machines, so as to vary the pitch of the fingers.